J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-2005 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package sun.rmi.transport; |
| 27 | |
| 28 | import java.io.IOException; |
| 29 | import java.io.ObjectOutput; |
| 30 | import java.rmi.MarshalException; |
| 31 | import java.rmi.NoSuchObjectException; |
| 32 | import java.rmi.Remote; |
| 33 | import java.rmi.RemoteException; |
| 34 | import java.rmi.server.LogStream; |
| 35 | import java.rmi.server.ObjID; |
| 36 | import java.rmi.server.RemoteCall; |
| 37 | import java.rmi.server.RemoteServer; |
| 38 | import java.rmi.server.ServerNotActiveException; |
| 39 | import java.security.AccessControlContext; |
| 40 | import sun.rmi.runtime.Log; |
| 41 | import sun.rmi.server.Dispatcher; |
| 42 | import sun.rmi.server.UnicastServerRef; |
| 43 | |
| 44 | /** |
| 45 | * Transport abstraction for enabling communication between different |
| 46 | * VMs. |
| 47 | * |
| 48 | * @author Ann Wollrath |
| 49 | */ |
| 50 | public abstract class Transport { |
| 51 | |
| 52 | /** "transport" package log level */ |
| 53 | static final int logLevel = LogStream.parseLevel(getLogLevel()); |
| 54 | |
| 55 | private static String getLogLevel() { |
| 56 | return (String) java.security.AccessController.doPrivileged( |
| 57 | new sun.security.action.GetPropertyAction("sun.rmi.transport.logLevel")); |
| 58 | } |
| 59 | |
| 60 | /* transport package log */ |
| 61 | static final Log transportLog = |
| 62 | Log.getLog("sun.rmi.transport.misc", "transport", Transport.logLevel); |
| 63 | |
| 64 | /** References the current transport when a call is being serviced */ |
| 65 | private static final ThreadLocal currentTransport = new ThreadLocal(); |
| 66 | |
| 67 | /** ObjID for DGCImpl */ |
| 68 | private static final ObjID dgcID = new ObjID(ObjID.DGC_ID); |
| 69 | |
| 70 | /** |
| 71 | * Returns a <I>Channel</I> that generates connections to the |
| 72 | * endpoint <I>ep</I>. A Channel is an object that creates and |
| 73 | * manages connections of a particular type to some particular |
| 74 | * address space. |
| 75 | * @param ep the endpoint to which connections will be generated. |
| 76 | * @return the channel or null if the transport cannot |
| 77 | * generate connections to this endpoint |
| 78 | */ |
| 79 | public abstract Channel getChannel(Endpoint ep); |
| 80 | |
| 81 | /** |
| 82 | * Removes the <I>Channel</I> that generates connections to the |
| 83 | * endpoint <I>ep</I>. |
| 84 | */ |
| 85 | public abstract void free(Endpoint ep); |
| 86 | |
| 87 | /** |
| 88 | * Export the object so that it can accept incoming calls. |
| 89 | */ |
| 90 | public void exportObject(Target target) throws RemoteException { |
| 91 | target.setExportedTransport(this); |
| 92 | ObjectTable.putTarget(target); |
| 93 | } |
| 94 | |
| 95 | /** |
| 96 | * Invoked when an object that was exported on this transport has |
| 97 | * become unexported, either by being garbage collected or by |
| 98 | * being explicitly unexported. |
| 99 | **/ |
| 100 | protected void targetUnexported() { } |
| 101 | |
| 102 | /** |
| 103 | * Returns the current transport if a call is being serviced, otherwise |
| 104 | * returns null. |
| 105 | **/ |
| 106 | static Transport currentTransport() { |
| 107 | return (Transport) currentTransport.get(); |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * Verify that the current access control context has permission to accept |
| 112 | * the connection being dispatched by the current thread. The current |
| 113 | * access control context is passed as a parameter to avoid the overhead of |
| 114 | * an additional call to AccessController.getContext. |
| 115 | */ |
| 116 | protected abstract void checkAcceptPermission(AccessControlContext acc); |
| 117 | |
| 118 | /** |
| 119 | * Service an incoming remote call. When a message arrives on the |
| 120 | * connection indicating the beginning of a remote call, the |
| 121 | * threads are required to call the <I>serviceCall</I> method of |
| 122 | * their transport. The default implementation of this method |
| 123 | * locates and calls the dispatcher object. Ordinarily a |
| 124 | * transport implementation will not need to override this method. |
| 125 | * At the entry to <I>tr.serviceCall(conn)</I>, the connection's |
| 126 | * input stream is positioned at the start of the incoming |
| 127 | * message. The <I>serviceCall</I> method processes the incoming |
| 128 | * remote invocation and sends the result on the connection's |
| 129 | * output stream. If it returns "true", then the remote |
| 130 | * invocation was processed without error and the transport can |
| 131 | * cache the connection. If it returns "false", a protocol error |
| 132 | * occurred during the call, and the transport should destroy the |
| 133 | * connection. |
| 134 | */ |
| 135 | public boolean serviceCall(final RemoteCall call) { |
| 136 | try { |
| 137 | /* read object id */ |
| 138 | final Remote impl; |
| 139 | ObjID id; |
| 140 | |
| 141 | try { |
| 142 | id = ObjID.read(call.getInputStream()); |
| 143 | } catch (java.io.IOException e) { |
| 144 | throw new MarshalException("unable to read objID", e); |
| 145 | } |
| 146 | |
| 147 | /* get the remote object */ |
| 148 | Transport transport = id.equals(dgcID) ? null : this; |
| 149 | Target target = |
| 150 | ObjectTable.getTarget(new ObjectEndpoint(id, transport)); |
| 151 | |
| 152 | if (target == null || (impl = target.getImpl()) == null) { |
| 153 | throw new NoSuchObjectException("no such object in table"); |
| 154 | } |
| 155 | |
| 156 | final Dispatcher disp = target.getDispatcher(); |
| 157 | target.incrementCallCount(); |
| 158 | try { |
| 159 | /* call the dispatcher */ |
| 160 | transportLog.log(Log.VERBOSE, "call dispatcher"); |
| 161 | |
| 162 | final AccessControlContext acc = |
| 163 | target.getAccessControlContext(); |
| 164 | ClassLoader ccl = target.getContextClassLoader(); |
| 165 | |
| 166 | Thread t = Thread.currentThread(); |
| 167 | ClassLoader savedCcl = t.getContextClassLoader(); |
| 168 | |
| 169 | try { |
| 170 | t.setContextClassLoader(ccl); |
| 171 | currentTransport.set(this); |
| 172 | try { |
| 173 | java.security.AccessController.doPrivileged( |
| 174 | new java.security.PrivilegedExceptionAction() { |
| 175 | public Object run() throws IOException { |
| 176 | checkAcceptPermission(acc); |
| 177 | disp.dispatch(impl, call); |
| 178 | return null; |
| 179 | } |
| 180 | }, acc); |
| 181 | } catch (java.security.PrivilegedActionException pae) { |
| 182 | throw (IOException) pae.getException(); |
| 183 | } |
| 184 | } finally { |
| 185 | t.setContextClassLoader(savedCcl); |
| 186 | currentTransport.set(null); |
| 187 | } |
| 188 | |
| 189 | } catch (IOException ex) { |
| 190 | transportLog.log(Log.BRIEF, |
| 191 | "exception thrown by dispatcher: ", ex); |
| 192 | return false; |
| 193 | } finally { |
| 194 | target.decrementCallCount(); |
| 195 | } |
| 196 | |
| 197 | } catch (RemoteException e) { |
| 198 | |
| 199 | // if calls are being logged, write out exception |
| 200 | if (UnicastServerRef.callLog.isLoggable(Log.BRIEF)) { |
| 201 | // include client host name if possible |
| 202 | String clientHost = ""; |
| 203 | try { |
| 204 | clientHost = "[" + |
| 205 | RemoteServer.getClientHost() + "] "; |
| 206 | } catch (ServerNotActiveException ex) { |
| 207 | } |
| 208 | String message = clientHost + "exception: "; |
| 209 | UnicastServerRef.callLog.log(Log.BRIEF, message, e); |
| 210 | } |
| 211 | |
| 212 | /* We will get a RemoteException if either a) the objID is |
| 213 | * not readable, b) the target is not in the object table, or |
| 214 | * c) the object is in the midst of being unexported (note: |
| 215 | * NoSuchObjectException is thrown by the incrementCallCount |
| 216 | * method if the object is being unexported). Here it is |
| 217 | * relatively safe to marshal an exception to the client |
| 218 | * since the client will not have seen a return value yet. |
| 219 | */ |
| 220 | try { |
| 221 | ObjectOutput out = call.getResultStream(false); |
| 222 | UnicastServerRef.clearStackTraces(e); |
| 223 | out.writeObject(e); |
| 224 | call.releaseOutputStream(); |
| 225 | |
| 226 | } catch (IOException ie) { |
| 227 | transportLog.log(Log.BRIEF, |
| 228 | "exception thrown marshalling exception: ", ie); |
| 229 | return false; |
| 230 | } |
| 231 | } |
| 232 | |
| 233 | return true; |
| 234 | } |
| 235 | } |